It is known that fluorinated alkanes of 1 to 5 carbon atoms, such as chlorofluorocarbons (hereinafter sometimes referred to as “CFCs”), hydrochlorofluorocarbons (sometimes referred to as “HCFCs”) and hydrofluorocarbons (sometimes referred to as “HFCs”), show volatility, stability, and non-flammability. Therefore, these fluorinated alkanes (sometimes referred to as “Freons”) have been used as refrigerants, working fluids, foaming agents, sprays, cleaning agents, dissolving agents, solvents, etc. and made contributions to industrial developments. Furthermore, these fluorinated alkanes have been widely used as blends of two or more kinds thereof. For example, there were commonly used mixed refrigerants R502, R507A, R404A, R407C and R401A according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards. The above mixed refrigerants are each prepared by mixing two or more kinds of Freons at a specific ratio for improvements in coefficient of performance, refrigeration cycle, non-flammability, global warming potential and the like. However, because of the volatility of the fluorinated alkanes, there occurs a composition change in the mixture by evaporation of any one of the Freons during use. The physical properties of the mixture vary due to such a composition change. Therefore, it is preferable to form an azeotrope or azeotrope-like composition in that the vapor phase produced by volatilization has the same or substantially the same composition as does the liquid phase. The above-mentioned refrigerant R502 (that is, a mixed refrigerant of R22 and R115) and refrigerant R507A (that is, a mixed refrigerant of R143a and R125) are known as azeotrope refrigerants because each of these refrigerants is in the form of an azeotrope mixture having vapor and liquid phase of exactly the same composition. The above-mentioned refrigerant R410A is known as an azeotrope-like refrigerant because its constituent components R32 and R125 do not form an azeotrope composition but form a mixture having vapor and liquid phases of substantially the same composition so that this mixture can be handled in practically the same manner as the azeotrope composition. The applications other than the refrigerant applications include water removing agents each prepared by blending a fluorinated alkane with an alcohol, and cleaning agents each prepared by adding a non-flammable fluorinated alkane to a flammable hydrocarbon solvent so as to achieve non-flammability and controlled cleaning power. Even in these applications of water removing and cleaning agent, as in the case of the refrigerant applications, it is preferable to form an azeotrope or azeotrope-like composition where the vapor phase produced by volatilization has the same or substantially the same composition as does the liquid phase.
It is also known that the fluorinated alkanes as mentioned above are very stable in the air and long in atmospheric lifetime and become a cause of global warming. For these reasons, fluorinated olefins of 2 to 5 carbon atoms (such as hydrofluoroolefins, hydrochlorofluoroolefins, chlorofluoroolefins, and fluoroolefins) have recently been proposed as substitutes for the above fluorinated alkanes. The fluorinated olefins, each of which has a double bond in the molecule, shows significantly high reactivity to OH radicals in the air as compared to the fluorinated alkanes with no double bond. The atmospheric lifetime of the fluorinated olefins is generally in days, whereas the atmospheric lifetime of the commonly used fluorinated alkanes such as HFC-365mfc, HFC-245fa and HFC-43-10 is in years. The fluorinated olefins, even if released into the air, get quickly decomposed and have less influence of global warming, ozone depletion, etc. Furthermore, it is reported that the fluorinated olefins have similar physical properties as those of the fluorinated alkanes and can be used for various applications such as refrigerants, working fluids, foaming agents, sprays, cleaning agents, dissolving agents, solvents, etc.
The fluorinated olefins can be improved in performance by blending other chemical species therewith as in the case of the fluorinated alkanes. For example, Patent Document 1 teaches that: an azeotrope-like binary solvent is formed by mixing (Z)-1-chloro-3,3,3-trifluoropropene with 1,1,2,2-tetrafluoro-1-methoxyethane; and the thus-formed binary solvent has good cleaning effect on various oils. However, specific reports on azeotrope or azeotrope-like compositions of fluorinated olefins are few in number as compared to those of fluorinated alkanes. Furthermore, documents about an azeotrope or azeotrope-like composition where fluorinated olefins are combined with each other are lesser in number.
Patent Document 2 has proposed a mixture of a fluorinated olefin of 3 carbon atoms and a general-purpose solvent. In Example 4 of Patent Document 2, a degreasing test of 1,2-dichloro-3,3,3-trifluoropropene alone has been disclosed. However, there is no description about geometrical isomer (E-isomer, Z-isomer) of 1,2-dichloro-3,3,3-trifluoropropene. Patent Documents 3 to 7 teach a resist remover, a buffing agent, an adhesive moisture removing solvent, and a dry cleaning agent relating to 1,2-dichloro-3,3,3-trifluoropropene, but give no description about the geometric isomers of 1,2-dichloro-3,3,3-trifluoropropene as in the case of Patent Document 2.